Draw works for drilling rig

ABSTRACT

A drilling apparatus includes a mast having a drill head arranged for travel longitudinally thereof. The drill head is capable of rotatably supporting a string of drill pipes within the mast. Hoisting and draw down cables are connected to the drill head for applying lifting or draw down forces to the latter. The hoisting and draw down cables are connected to a single winch drum in such a fashion that when the drum is rotated one of the cables is tensioned and wraps on the drum in a single layer while the other cable unwraps therefrom whereby lifting or draw down forces are applied to the drill head so that the latter is caused to travel along the mast in a direction determined by the direction of rotation of the drum. The drum is dimensioned such that not more than one layer of cable need wrap on a drum regardless of the position of the drill head within the mast. The hoisting cable is connected adjacent one end of the drum while the draw down cable is connected adjacent its other end.

United States Patent [1 1 Wilderman 1 Feb. 20, 1973 [54] DRAW WORKS FOR DRILLING RIG [75] Inventor: Giles H. Wilderman, Calgary, Al-

berta, Canada [73] Assignee: Kenting Drilling Limited, Calgary,

Alberta, Canada [22] Filed: Jan. 27, 1971 [21] Appl. No.: 110,116

Primary Examiner-Emest R. Purser Attorney-Cushman, Darby & Cushman [57] ABSTRACT A drilling apparatus includes a mast having a drill head arranged for travel longitudinally thereof. The drill head is capable of rotatably supporting a string of drill pipes within the mast. Hoisting and draw down cables are connected to the drill head for applying lifting or draw down forces to the latter. The hoisting and draw down cables are connected to a single winch drum in such a fashion that when the drum is rotated one of the cables is tensioned and wraps on the drum in a single layer while the other cable unwraps therefrom whereby lifting or draw down forces are applied to the drill head so that the latter is caused to travel along the mast in a direction determined by the direction of rotation of the drum. The drum is dimensioned such that not more than one layer of cable need wrap on a drum regardless of the position of the drill head within the mast. The hoisting cable is connected adjacent one end of the drum while the draw down cable is connected adjacent its other end.

5 Claims, 4 Drawing Figures PATENTEDFEB20'1975 SHEET 10F 3 MAMQXV A FIG. I

PATENTED FEB20 I975 SHEET 20F 3 PATENTEDFEBZO 1m 3', T 1 7, 205

sum 3 0F 3 //////////l I I//// I/ DRAW WORKS FOR DRILLING RIG The present invention relates generally to drilling rigs and particularly to improvements in the drawworks for applying lifting or drawdown forces to the drill string.

Most oil and gas wells are drilled by the rotary drilling method wherein a drill bit is mounted on the end of a drill string and rotated within the well bore hole by the drill string and suitable drill string rotating machinery. The rotating machinery may include a rotary turntable positioned on the drilling deck or platform and through which the drill string extends; alternatively it may include a hydraulic or electric motor suitably mounted in the drill mast and adapted for connection to the uppermost pipe of the drill string.

When using the rotary drilling method, additional sections of pipe are added to the drill string as the well becomes deeper thus increasing the total weight of the drill string and hence the amount of weight available to produce a downward thrust on the drill bit. in deep well boring operations the available weight frequently exceeds that which the drill bit can withstand, thus making it necessary to apply an upward or lifting force on the drill string. The prior art has provided various automatic devices for applying the necessary lifting force to prevent damage to the drill bit. On the other hand there are occasions when it is necessary to apply a downward force to the drill string to effect the desired rate of penetration of the drill bit through the underlying earth formations. The need for drawdown force application arises, for example, when drilling relatively shallow bore holes; in such cases the total drill string weight may not be sufficient especially if hard earth formations are encountered. Similar conditions are often encountered during the initial phases of a deep well operation, i.e., before a sufficient number of lengths of drill string have been added as to provide the necessary weight on the bit.

Prior art rotary drilling apparatus commonly includes an upright mast having a drill head arranged for travel longitudinally within the mast. The drill head is adapted to rotatably support a length of the drill string and is commonly connected to the upper end of the latter by means of a threaded connection. In order to effect lifting or drawdown of the drill string, separate drawdown and lifting cable systems are connected to the drill head and suitable winches are employed to wind up and unreel the cables as required. The prior art winching systems commonly employed separate winch drums for the drawdown and lift cables. While reasonably satisfactory performance has been obtained, many of these arrangements have been unduly complex and costly and have led to excessive cable wear and damage.

in accordance with the present invention drilling apparatus of the general nature described above is provided which employs a single winch drum for both the drawdown and lift cables. The system is arranged such that as one cable is paid out from the drum the other cable is wound up thereon and the drum is made sufficiently large so that not more than a single layer of cable wraps thereon at any time. This arrangement provides simplicity of construction, equal rates of pay out of the hoist and pull down cables, and a reduction in the amount of cable wear and/or damage due to the single wrap layer feature.

Accordingly therefore the present invention provides, in one aspect, a drilling apparatus comprising a mast, a drill head arranged for travel longitudinally along the mast, said drill head being capable of sup porting a string of drill pipe rotatably within the mast, hoisting means including a hoisting cable associated with the drill head to enable the latter to lift the drill string, and drawdown means including drawdown cable associated with the drill head to enable the latter to effect drawdown of the drill string, the hoisting and drawdown means further including a winchdrum and drive means for rotating same, said hoisting cable and said drawdown cable being connected to said drum in such a fashion that when the drum is rotated one of said cables is tensioned and wraps on said drum in a single layer while the other unwraps therefrom whereby lifting or drawdown forces are applied to the drill head so that the latter is caused to travel along the mast in a direction determined by the direction of rotation of the drum, said drum being dimensioned such that not more than one layer of cable need wrap on said drum regardless of the position of the drill head within the mast.

An illustrative embodiment of the invention will now be described with reference being had to the drawings wherein:

FIG. 1 is an elevation view of a portion of a drilling rig employing the principles of the present invention;

FIG. 2 is a diagrammatic view of the drill string hoisting and drawdown system;

FIGS. 3 and 4 are diagrammatic views of the winch drum showing the disposition of the hoist and drawdown cables thereon for the up and down, positions of the drill head.

With reference to the drawings it will be seen that there is provided a drilling rig 10 including a carrier or platform 12, mounted on wheels 14 for mobility. Levelling jacks 16 are extendable to support the platform 12 during the drilling operation.

A mast 18 is shown in FIG. I in a generally upright position. Mast 18 is pivotally connected at points 20 to mast support assembly 22 so that the mast may be lowered to a horizontal position when the drilling apparatus is being transported from one place to another.

In order to facilitate the handling of lengths of drill stem, a swinging pipe handling arm 24 may be em ployed to lift the lengths of drill stem from the horizontal racking position to an upright position for connection to the uppermost end of the drill string in the manner well known in the art. In order to carry this out automatically, power tongs 26 are provided along with power operated slips 28 which operatein the manner well known in the art.

A drill head 30 is disposed within and arranged for travel longitudinally of the mast on suitable guide means (not shown). The drill head shown is provided with a hydraulic motor 32 capable of rotating the drill stem to effect drilling; however it should be realized that the drill string may be powered in other. ways e.g., by mechanical drives or turntable-type drives. A threaded connection piece 33 adapted to be threaded into the upper end of a drill string extending along drilling axis A is rotatably mounted in drill head 30 for rotation by motor 32. A powered winch drum arrangement 34 mounted on the mast I8 effect hoisting and drawdown of drill head 30, as will be described more fully below.

The drill mast 18, the drill head 30 and the means for moving same longitudinally of the mast are shown diagrammatically in FIG. 2, it being realized that the components shown are well out of their usual proportions in order to better illustrate the principles involved. Details well known in the art such as the means for guiding the drill head longitudinally of the mast etc. are not shown.

The winch drum arrangement 34 includes a single winch drum 36 of uniform diameter throughout its length which is driven in either direction by winch drive assembly 38. Various winch drives are available on the market, e.g., the Gearmatic winch as well as others.

In order to hoist the drill head 30 upwardly a hoisting line 38 (shown as a solid line) is provided which has its one end connected adjacent one end 36a of the hoisting drum while its opposing end is firmly anchored at 40 to a fixed point on the drilling apparatus. Hoisting line 38 passes upwardly from its point of connection to winch drum 36 over idler sheave 42 mounted adjacent the upper end of the mast; the line 38 then passes downwardly and around sheave 44 mounted on drill head 30, thence upwardly and over the two sheaves 45 adjacent the top of the mast 18, then downwardly around sheave 46 mounted on drill head 30 and again upwardly to sheave 48 mounted adjacent the top of the mast and then down to the dead end or anchor point 40. The hoisting arrangement just described is a four string arrangement in that a mechanical advantage of four is provided.'lt will be seen from FIG. 2 that as hoist cable 50 is wound up on drum 36, the drill head 30is lifted upwardly.

The drill head drawdown arrangement also is a four string arrangement. The drawdown cable 50 (shown as a dashed line) is connected at its one end to winch drum 36 adjacent end 36b (which is opposite end 360) of the latter, and at its other end to a dead end or anchor point 52 fixed to the drilling rig. As shown in FIG. 2 drawdown cable passes upwardly from winch drum 36 to sheave 54 mounted at the top of mast l8, thence downwardly and around sheave 56 mounted adjacent the lower end of.mast 18, thence upwardly and around sheave 58 mounted on drill head 30, then down and around sheaves 60 adjacent the mast bottom, then up and around a further sheave 62 mounted on the drill head'and then down to dead end 52.

While four-string arrangements are shown, it should be realized that other string arrangements (2 string, 6 string for example), are possible so long as the number of strings used in the hoist system yield the same mechanical advantage as is yielded by the string arrangement in the drawdown system.

The drawdown and hoist cables 50 and 38 are arranged such that as winch drum 36 is rotated, one of said cables wraps on the drum in a single layer while the other cable unwraps therefrom thus ensuring equal rates of pay out and take'up of the two cables at all times. FIG. 3 illustrates the disposition of the cables 38 and 50 on the winch drum when the drill head is ad jacent its uppermost position. It'will be seen that a major portion. of the surface of the winch drum is covered with a single layer of the hoist cable 38 which layer extends from the end 360 of the hoist drum to a position spaced from the opposing end 36b of the drum. A single layer of drawdown cable 50 extends from the opposing end of the drum 36b for a relatively short distance towards the opposing end. FIG. 4 illustrates the other extreme condition when the drill head 30 is in its lowermost position. In this case a single. layer of drawdown cable 36 extends over a major portion of the drum surface with only a few turns of hoist cable remaining on the drum adjacent end 36a thereof.

The diameter and the length dimensions of the winch drum are made sufficiently great so that not more than a single layer of cable need wrap thereon at any one time in order to accommodate the required lengths of the two cables.. A suitable traverse mechanism may be employed to assist in winding the cables on the drum 36 in single layer fashion; however such mechanism is not generally needed especially if the cables are supplied to the drum generally at right angles to the axis of drum rotation at all times. In the arrangement shown in FIG. 2 both the hoist and drawdown cables pass downwardly towards the drum from sheaves 42 and 54 high up on the mast, and since the distance between these sheaves and the drum is large compared with the drum length, the cables approach the drum 36 roughly at right angles to the axis of rotation of the latter at all times.

lclaim:

1. Earth drilling apparatus comprising a mast, a drill head arranged for travel longitudinally along the mast, said drill head being adapted for attachment to the upper end of a string of drill pipe to support the latter within the mast during a drilling operation, hoisting means including a hoisting cable system having a hoisting cable operatively connected with the drill head to enable lifting of the drill string to be effected and drawdown means including a drawdown cable system having a drawdown cable operatively connected with the drill head to enable drawdown of the drill string to be effected, the hoisting and drawdown means further including a single winch drum and drive means for rotating same in both directions, said hoisting and drawdown cable systems being arranged such and being operatively connected to said drill head and said single winch drum in such a fashion that when the drum is rotated one of said cables is tensioned and wraps on said drum in a single layer while the other cable unwraps from the drum to apply lifting or drawdown forces, as the case may be, to the drill head so that the latter is caused to travel along .the mast in a direction determined by the direction of rotation of the drum, said single winch drum being dimensioned such that not more than one layer of cable need wrap on said drum regardless of the position of the drill head within the mast.

2. Earth drilling apparatus according to claim I, wherein one end only of each of the hoisting and drawdown cables is connected to said winch drum while the other end of each said cable is anchored in a fixed position to another part of said drilling apparatus.

3. Earth drilling apparatus according to claim 1 wherein an end of said hoisting cable is secured to said drum adjacent one end of the latter with an end of said drawdown cable being secured to said drum adjacent the other end of said drum.

4. Earth drilling apparatus according to claim 3 wherein each of said hoisting and drawdown cable systems each comprise a multi-string cable arrangernent whereby to provide a mechanical advantage greater than one for both of said cable systems.

5. Earth drilling apparatus according to claim 4, wherein one end only of each of the hoisting and drawdown cables is connected to said winch drum while the 5 other end of each said cable is anchored to another part of said drilling apparatus.

UNITED STATES PATENT [OFFICE QER'HFICATE 0F CORRECTION Patent No. 3,717,205 v Dated February 20, 1973 InVentor(s) Ho I It is certified that efror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the above-identified patent please add the following to the front page format after the ir mformatioh in paragraph I [30] Foreign Application Priority Data February 16, 197 Canada 7 ,9135

Signed and sealed this 20th day of November 1973.

(SEAL) Attest:

EDWARD M.FLETCHEB,JR. RENE D. TEG'I'MEYER Attesting Officer." Acting Commissioner of Patents 

1. Earth drilling apparatus comprising a mast, a drill head arranged for travel longitudinally along the mast, said drill head being adapted for attachment to the upper end of a string of drill pipe to support the latter within the mast during a drilling operation, hoisting means including a hoisting cable system having a hoisting cable operatively connected with the drill head to enable lifting of the drill string to be effected and drawdown means including a drawdown cable system having a drawdown cable operatively connected with the drill head to enable drawdown of the drill string to be effected, the hoisting and drawdown means further including a single winch drum and drive means for rotating same in both directions, said hoisting and drawdown cable systems being arranged such and being operatively connected to said drill head and said single winch drum in such a fashion that when the drum is rotated one of said cables is tensioned and wraps on said drum in a single layer while the other cable unwraps from the drum to apply lifting or drawdown forces, as the case may be, to the drill head so that the latter is caused to travel along the mast in a direction determined by the direction of rotation of the drum, said single winch drum being dimensioned such that not more than one layer of cable need wrap on said drum regardless of the position of the drill head within the mast.
 1. Earth drilling apparatus comprising a mast, a drill head arranged for travel longitudinally along the mast, said drill head being adapted for attachment to the upper end of a string of drill pipe to support the latter within the mast during a drilling operation, hoisting means including a hoisting cable system having a hoisting cable operatively connected with the drill head to enable lifting of the drill string to be effected and drawdown means including a drawdown cable system having a drawdown cable operatively connected with the drill head to enable drawdown of the drill string to be effected, the hoisting and drawdown means further including a single winch drum and drive means for rotating same in both directions, said hoisting and drawdown cable systems being arranged such and being operatively connected to said drill head and said single winch drum in such a fashion that when the drum is rotated one of said cables is tensioned and wraps on said drum in a single layer while the other cable unwraps from the drum to apply lifting or drawdown forces, as the case may be, to the drill head so that the latter is caused to travel along the mast in a direction determined by the direction of rotation of the drum, said single winch drum being dimensioned such that not more than one layer of cable need wrap on said drum regardless of the position of the drill head within the mast.
 2. Earth drilling apparatus according to claim 1, wherein one end only of each of the hoisting and drawdown cables is connected to said winch drum while the other end of each said cable is anchored in a fixed position to another part of said drilling apparatus.
 3. Earth drilling apparatus according to claim 1 wherein an end of said hoisting cable is secured to said drum adjacent one end of the latter with an end of said drawdown cable being secured to said drum adjacent the other end of said drum.
 4. Earth drilling apparatus according to claim 3 wherein each of said hoisting and drawdown cable systems each comprise a multi-string cable arrangement whereby to provide a mechanical advantage greater than one for both of said cable systems. 